header {
  text-align: center;
}

table {
  table-layout: fixed;
  margin: 30px auto 0px;
  background-color: #828282;
}

i {
  margin: 0 5px;
  font-style: normal;
  color: red;
}

b {
  font-weight: 400;
  color: red;
}

button {
  width: 60px;
  margin: 20px;
}

span {
  margin: 0px 20px;
}

table td {
  width: 26px;
  height: 26px;
  cursor: pointer;
  background-color: #C0C0C0;
  background-position: center;
  background-repeat: no-repeat;
  box-shadow: 4px 0px 1px #FFFFFF inset, 0px 4px 1px #FFFFFF inset, 0px -4px 1px #828282 inset, -4px 0px 1px #828282 inset;
}

table td.oncl {
  box-shadow: 4px 0px 1px #C4C4C4 inset, 0px 4px 1px #C4C4C4 inset;
}

.mask {
  display: none;
  position: absolute;
  top: 122px;
  left: 0;
  right: 0;
  margin: auto;
  background-color: rgba(0, 0, 0, .1);
}

.mask .popup {
  position: absolute;
  top: 0;
  bottom: 0;
  left: 0;
  right: 0;
  margin: auto;
  display: flex;
  flex-direction: column;
  justify-content: center;
  text-align: center;
  width: 150px;
  height: 60px;
  border-radius: 8px;
  font-weight: 700;
  background-color: rgba(240, 240, 240, 0.7);
}